The present invention relates to an apparatus for driving devices which are "supplementary" to, i.e., operated by, an internal combustion engine.
In the internal combustion engine art, for many years, attempts have been made to provide compact internal combustion engines having one or more of a variety of supplementary devices, such as an air compressor, an alternator, and an oil pump, and additional devices, such as a water pump and a supercharger. All of these devices are conventionally driven by an engine crankshaft. One such internal combustion engine is known from, for instance, Japanese Unexamined Utility Model Publication no. 62-71,340.
In attempts to provide a compact engine which has a short length and is equipped with supplementary devices driven by an engine crankshaft, various "V-type" internal combustion engines have recently been developed. In such an engine, an engine camshaft can be rotatably connected to overhead camshafts and any supplementary devices by both a camshaft timing belt and a supplementary device drive belt, respectively. In order to arrange the belts so that they do not interfere with each other, the belts must be placed in different spatial planes located at different distances from an end surface of the engine However, locating the belts in such planes causes the engine to have a large overall length and adversely affects the ability to make the engine compact in size In particular, in an engine equipped with a supercharger in addition to various other supplementary devices, the supercharger must be rotatably connected to the crankshaft by yet another belt. Because this other belt must be arranged so that it does not interfere with belts operating the overhead camshafts and the supplementary devices, the engine is made even larger in overall length if it includes a supercharger. In addition, if all of the belts are driven by the crankshaft, vibrations of the crankshaft, caused by a piston reaction, are transmitted to the camshafts. Such vibrations also can exert excess tension on the belts operating the supplementary devices and the supercharger. This adversely affects the durabilities of the belts.